A typical high power, radio frequency (RF) semiconductor device may include one or more input leads, one or more output leads, one or more transistors, bond-wires coupling the input lead(s) to the transistor(s), and bond-wires coupling the transistor(s) to the output lead(s). The bond-wires have inductive reactance at high frequencies, and such inductances are factored into the design of input and output impedance matching circuits for a device. In some cases, input and output impedance matching circuits may be contained within the same package that contains the device's transistor(s). More specifically, an in-package, input impedance matching circuit may be coupled between a device's input lead and a control terminal (e.g., the gate) of a transistor, and an in-package, output impedance matching circuit may be coupled between a current conducting terminal (e.g., the drain) of a transistor and a device's output lead.
In the field of amplifier design, it is becoming necessary to perform concurrent multi-band, broadband amplification. In order to successfully design a wideband Doherty Power Amplifier (PA) for concurrent multi-band, broadband operation, it is necessary to enable a good broadband fundamental match, to handle harmonic frequency interactions, and to enable a wide video bandwidth (VBW). The handling of harmonic frequency interactions at the input and output impedance matching networks of a PA becomes especially important for gallium nitride (GaN)-based Doherty PAs. In particular, frequency dispersion introduced across the harmonic band of a Doherty PA results in (i) increased sensitivity of interactions between the fundamental match impedance and harmonic termination, and (ii) the optimum fundamental load at the output of the PA no longer being constant, which effectively limits the PA bandwidth. Hence there is a pressing need to develop broadband harmonic termination.